Apparatus and methods for controlling the amount of fuel injected into an internal combustion engine

ABSTRACT

The amount of fuel injected into an inlet passage of an internal combustion engine leading to a cylinder thereof is regulated by a control device in response to suction pressure in the passage and to the degree of opening of a throttle valve in the passage. This is achieved by connecting in parallel to the control device, a first suction opening in the passage downstream of the valve, and a second suction passage immediately proximate the valve so as to lie downstream thereof when the valve is closed but to gradually be positioned upstream of the valve as it opens.

United States Patent Date et a1.

1 51 June 20, 1972 [72] Inventors: Tasuku Date, Tokyo; Eiichi l-lashimoto,

Niiza-machi, both of Japan [73] Assignee: Honda Giken Kogyo Kabushiki Kaisha,

Tokyo, Japan 22 Filed: Nov. 2, 1970 211 Appl.No.: 86,192

[30] Foreign Application Priority Data May 21, 1970 Japan ..45l42903 [52] US. Cl. ..123/140 MP, 123/140 MC, 123/139 AW, 123/119 R [51 Int. (1 OZd l/06 [58] Field of Search ..123/140 MP, 140 MC, 139 AW [56] References Cited UNlTED STATES PATENTS 2,063,848 12/1936 Meyer et a1. 123/140 MP 2,093,984 9/1937 Schweizer ..123/ 140 MP 2,132,446 10/1938 Schweizer ,,...123/140 MP 2,623,510 12/1952 Schweizer ..123/140 MP 2,633,115 3/1953 Waring ....123/140 MP 2,841,131 7/1958 Zupancic ..123/140 MP Primary Bummer-Laurence M. Goodridge Assistant Examiner-Cort Flint Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT The amount of fuel injected into an inlet passage of an internal combustion engine leading to a cylinder thereof is regulated by a control device in response to suction pressure in the passage and to the degree of opening of a throttle valve in the passage. This is achieved by connecting in parallel to the control device, a first suction opening in the passage downstream of the valve, and a second suction passage immediately proximate the valve so as to lie downstream thereof when the valve is closed but to gradually be positioned upstream of the valve as it opens.

7 Claims, 2 Drawing Figures PATENTEDJUHZO 1972 3,670,710

FIG!

C (07am WE /9') SUCTION NEG/1 T/ v5 PRESSURE (m m L INJ'ECT/ON AMOUNT V Z-C M INVENTOR (7W Pei APPARATUS AND METHODS FOR CONTROLLING THE AMOUNT OF FUEL INJECTED INTO AN INTERNAL COMBUSTION ENGINE BRIEF SUMMARY OF THE INVENTION The invention relates to fuel injection control in internal combustion engines and particularly to methods and apparatus for controlling fuel injection in a rational and efficient manner.

It is known in a fuel injection type internal combustion engine to control the amount of fuel injected by a suction pressure in the engine. In general, however, the required amount of fuel injection varies not only with change of the suction pressure but also with change of the open degree of the throttle valve, i. e., engine speed, and, therefore, it is preferable that the control also take this into consideration.

An object of this invention is to provide an apparatus in which the suction pressure is compensated in response to the open degree of the throttle valve and accordingly the control is effected by the suction pressure modulated by the open degree of the throttle valve.

The invention is characterized by a construction in which an engine suction passage having a butterfly type throttle valve is provided with a main negative pressure opening situated behind the throttle valve and also with a subsidiary negative pressure opening situated at a position which lies downstream of the valve when the valve is closed but faces the edge of the valve when the valve is slightly opened, and the openings being coupled such that the negative pressures therein are combined to provide a resultant negative pressure.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a section side view of a portion of one embodiment according to this invention; and

FIG. 2 is a graph showing the characteristic curve of suction pressure vs. fuel injection amount for explaining the operation of the embodiment of the invention.

DETAILED DESCRIPTION Referring to the drawing, numeral 1 denotes the main body of an internal combustion engine, numeral 2 denotes a suction valve opening therein, numeral 3 denotes a suction passage connected thereto, and numeral 4 denotes a butterfly type throttle valve in passage 3. This suction passage 3 is provided with a main negative pressure sensing opening 5 situated downstream of throttle valve 4, i.e., on the engine side in the drawing, and this opening 5 is in communication with a pressure responsive type control apparatus 8 for regulation of the injection quantity in a fuel injection device connected to a fuel injection nozzle 6. The control apparatus 8 is known and comprises, for instance, a pressure responsive type diaphragm, and when the fuel injection apparatus comprises, for instance, a cam push type plunger pump, it is so constructed that the lift degree of the cam is adjusted in accordance with the deflection degree of the diaphragm.

The above overall construction is not different from conventional construction and as it stands, there is the following deficiency. Namely, in general, the required amount of fuel injection changes not only in dependence on the change of the suction pressure in passage 3 but also on the open degree of the throttle valve 4. In the case when the open degree of the valve is changed, for instance, 5 degrees, 10 degrees and 19 degrees, the required fuel injection amount for each engine speed, for instance, 2,000 r.p.m., 3,000 r.p.m. changes as shown by curves a, b and c in FIG. 2, so that when the characteristic feature of the fuel injection control apparatus is set as a line A also shown in FIG. 2, there is caused a lack of fuel especially for comparatively large open degrees of the throttle valve.

If, by way of example, the open degree of the throttle valve is l9 degrees and the engine speed is 7,000 r.p.m., it corresponds to a point P on the curve C at which a negative pressure of about 90 mm. Hg is produced and the required amount of fuel in this case is about 18 cubic mm. According to the line A, however, when the negative pressure is mm. Hg, about 15 cubic mm. of the amount of fuel injection is obtained at point Q on said line A and thus there is actually a deficiency of l8l5=3 cubic mm.

For compensating this deficiency, this invention contemplates a construction as follows:

A subsidiary negative pressure opening 7 is provided in the suction passage 3 at a position which is downstream of the throttle valve 4 when the valve 4 is closed but faces the end edge 4a of the throttle valve 4 when the valve 4 has been slightly opened. The opening 7 and the opening 5 are connected in parallel with one another to a pressure receiving portion of the control apparatus 8 so that the control may be effected by the resultant of the negative pressures obtained at the two openings 7 and 5. When the negative pressure obtained at the opening 7 is considered, this is only the regular suction pressure produced behind the throttle valve 4 when the valve 4 is fully closed, but as the valve 4 is gradually opened, the opening 7 gradually senses a smaller negative pressure by being subjected to the atmospheric pressure upstream of the throttle valve 4. Consequently, the resultant of the negative pressures obtained at the two openings 7 and 5 tends to be of nearly the same characteristic feature. In other words, the suction pressure sensed is so compensated that the same is much smaller in magnitude of negative pressure in response to increase of the open degree of the throttle valve as shown by curves a, b and c in FIG. 2. If, accordingly, the control is thus carried out thereby, the amount of fuel injection is increased in accordance with the increase of the open degree of the throttle valve so as to approach the line A in FIG. 2. Namely, if there is now considered the case when, for instance, the open degree of the throttle valve is 19 degrees and the engine speed is 7,000 r.p.m., the suction pressure of about 90 mm. Hg'at the Point P is sensed and it is modulated so as to be about 60 mm. Hg at the point R, so that the injection amount becomes about 19 cubic mm. from the point S on the line A corresponding thereto and thus the injection amount which is obtained is close to the required 18 cubic In the illustrated example, the subsidiary negative pressure opening 7 is designed to branch into two openings correspond ing to 10 degrees and 19 degrees of the degree of opening of the throttle valve, respectively, but, of course, this invention is not limited thereto.

Thus, according to this invention, the suction pressure is sensed while being compensated in response to the change of the degree of opening of the throttle valve so that the control of the fuel injection amount based thereon is effected depending on both the-suction negative pressure and the degree of opening of the throttle valve whereby the operation of the engine can be improved in comparison with the case when the control is'efi'ected only by the regular suction negative pressure.

The openings 5 and 7 are placed in diarnetric opposition to one another at opposite sides of the passage 3 to minimize their influence on one another.

What is claimed is:

1. Apparatus for sensing suction pressure for control of the amount of fuel injection in an internal combustion engine, said apparatus comprising an engine suction passage having a butterfly type throttle valve therein, the valve being movable between a closed position and open positions, said passage being provided with a main negative pressure opening situated down stream of the throttle valve and also with a subsidiary negative pressure opening situated at a location which lies downstream of the throttle valve when the valve is closed but faces the edge of the throttle valve when the valve is slightly opened and then lies upstream of the valve when it becomes increasingly opened, said main opening always remaining downstream of the throttle valve, said openings being coupled such that the negative pressures in the two openings are combined to provide a resultant negative pressure.

2. Apparatus as claimed in claim 1 wherein said openings are connected in parallel.

3. Apparatus as claimed in claim 2 wherein the subsidiary opening has a plurality of branched portions extending into said passage.

4. Apparatus as claimed in claim 2 wherein the main and the subsidiary openings are at opposite sides of said passage.

5. Apparatus as claimed in claim 4 wherein said openings are diametrically opposed.

6. Apparatus as claimed in claim 1 wherein a control device regulates fuel flow to a fuel injection noule communicating with said passage, said openings being connected in parallel to said control device.

response to said resultant pressure.

t '0 i I 

1. Apparatus for sensing suction pressure for control of the amount of fuel injection in an internal combustion engine, said apparatus comprising an engine suction passage having a butterfly type throttle valve therein, the valve being movable between a closed position and open positions, said passage being provided with a main negative pressure opening situated downstream of the throttle valve and also with a subsidiary negative pressure opening situated at a location which lies downstream of the throttle valve when the valve is closed but faces the edge of the throttle valve when the valve is slightly opened and then lies upstream of the valve when it becomes increasingly opened, said main opening always remaining downstream of the throttle valve, said openings being coupled such that the negative pressures in the two openings are combined to provide a resultant negative pressure.
 2. Apparatus as claimed in claim 1 wherein said openings are connected in parallel.
 3. Apparatus as claimed in claim 2 wherein the subsidiary opening has a plurality of branched portions extending into said passage.
 4. Apparatus as claimed in claim 2 wherein the main and the subsidiary openings are at opposite sides of said passage.
 5. Apparatus as claimed in claim 4 wherein said openings are diametrically opposed.
 6. Apparatus as claimed in claim 1 wherein a control device regulates fuel flow to a fuel injection nozzle communicating with said passage, said openings being connected in parallel to said control device.
 7. A method of controlling the fuel injection in an internal combustion engine, said method comprising sensing the negative pressure of supply air flowing downstream of a throttle valve in the inlet passage leading to a cylinder of an internal combustion engine, sensing an auxiliary pressure in the inlet passage at a location immediately downstream of the valve when the latter is closed and which gradually becomes disposed upstream of the valve as the latter opens, combining the two pressures to provide a resultant negative pressure, and controlling the amount of fuel injected into the passage in response to said resultant pressure. 